Wireless technology is acquiring a digital nature, due to the increasing use of digital modulation formats as a way to increase spectral efficiency. Traditional test instruments served as excellent tools for analyzing analog transmissions. But with the growing number of digitally modulated wireless signals, different measurement tools are needed. Tektronix (www.tek.com) has offered its RSA3000B series of real-time spectrum analyzers for several years, and is making the technology more affordable with the latest additionsthe RSA3300B and RSA3408B models.

Digital modulation formats and a growing use of time-varying signals that operate with burst and hopping modes challenge capture by even the best traditional swept-frequency spectrum analyzers. The analyzers allow triggering on signals in the frequency domain in order to capture transient events that would otherwise be missed by a traditional sweep of frequency.

Introduced about two years ago, Tektronix's high-performance RSA- 6000A line provides as much as 110 MHz real-time bandwidth for capturing widely modulating signals. The three new RSA3000B series models offer less instantaneous measurement bandwidth, but considerable test capability for all but the most wideband modulated signals. The new models include the RSA3003B with measurement range of DC to 3 GHz and 15-MHz real-time bandwidth the RSA3008B with frequency range of DC to 8 GHz and 15-MHz real-time bandwidth, and the RSA3408B with frequency range of DC to 8 GHz and 36-MHz real-time bandwidth. The first two instruments feature 70-dB spuriousfree dynamic range (SFDR) while the RSA3408B delivers 73-dB SFDR.

The new RSA instruments incorporate the firm's DPX(TM) waveform image processor technology with a parallel processing architecture that performs as many as 48,000 spectrum measurements per second to produce a live spectral display that reveals transient signals. The DPX technology continuously executes discrete Fourier Transform (DFT) analysis to convert captured time-domain data into the frequency domain. Signals are shown on a full-motion display with variable color-graded persistence that makes is easier to identify anomalous signals. With each update, the power level values at each frequency across the capture bandwidth are recorded, and the incidence of power over time at each frequency is shown by varying colors on the display. The instruments also boast frequency-mask-trigger (FMT) functionality for triggering on brief or unique patterns of events in the frequency domain. Combined with the analyzers' wide dynamic ranges, the FMT capability can capture even weak transient signals in the presence of strong signals. It is ideal for observing unique events as part of radio communications testing and surveillance operations, and can analyze modulation switching on software-defined radios (SDRs) and rogue pulses in radar systems. The RSA3303B and RSA3308B analyzers can detect transients as brief as 41 s while the RSA3408B can grab transients as short as 31 s.